Petcock fiber washer leak

Liftedzuki

XS650 Addict
Messages
262
Reaction score
73
Points
28
Location
Kennewick, wA
I have a new petcock, screw washer and fiber wssher.

One screw keeps leaking no matter what. You would think the screw had a hole through the middle

Should I try using copper washers?
 
I’ve had that problem. Order yourself a tube of Hylomar Blue gasket compound. It was developed by Rolls Royce for aircraft use and man, does it work.

You might find it at an airport where small aircraft are repaired or just go on the web.

A little dab of that and the leak should stop.
 
I use just the screw (new or very well cleaned up on the wire wheel) and the fiber washer, not the other metal washer, and never had any leaks with many installations. I did a thread on this, called Installing Mikes' Petcock for Later Models.
 
I also have had issues with Mikes petcocks leaking, i had to take the rubber seal out and flip and turn it and its been good
since BUT I don't trust them.Wish I had originals, maybe Yamaha still makes them, anyone know?
 
I’ve had that problem. Order yourself a tube of Hylomar Blue gasket compound. It was developed by Rolls Royce for aircraft use and man, does it work.

You might find it at an airport where small aircraft are repaired or just go on the web.

A little dab of that and the leak should stop.

This will work....Hi Pete
 
Yes; no metal washer, the threads are not part of the seal. I reuse the stock washers exclusively. But with lots of parts around I can find one, razor blade it off a petcock and reinstall. That's a tricky area, tough to tell a tank petcock seal leak from a screw head leak. I remove all paint from the tank, use super glue or epoxy to seal the paint edge. and replace the oring or shaped seal with a "fatter" o-ring helped into place with a little bent tool or small screwdriver while tightening the screws.
 
Mine poured gas out like crazy as well when I first tried to install it.

Copper washers solved the problem. Not a drip for over a year. I'm trying to remember if I used teflon on the threads - but i can't remember.
 
You can still get the petcock washers new from Yamaha. They work really well.

The original ones I had from MikesXS disintegrated and caused a major leak from an otherwise good petcock.
 
On vacation Pete..... way down in Tasmania, 23rd wedding anniversary.......Bike is tucked up at home in the tropics...

IMG_4841.jpg
 
I have used copper washers with great success, but I freshly anneal them prior to use by heating then to a dull red on the gas stove. If you drop them immediately into cold water it will clean the oxide coating off, or just let them cool and give them a gentle brush with a fine wire brush.

The washers need to be a firm fit on the bolts which have quite a substantial radius where the shank meets the head. Compare one to your average M6 bolt to see the difference. I guess this radius is very important for the sealing process.
 
If you get a slight leak then try annealing the washers. It will soften then up and make a good seal - Best of luck.
 
Agreed - and to do that, just heat them up with a small torch and then let them cool down in the air.
 
..... or drop them straight into water and it will remove the oxide layer and not affect the softness - Copper will not harden with the rapid cooling.
 
Back
Top